Electrophysiological and immunocytological demonstration of cell-type specific responses to hypoxia in the adult cat carotid body

Chung Long Chou, James S.K. Sham, Brian Schofield, MacHiko Shirahata

Research output: Contribution to journalArticle

Abstract

We have recently shown two types of cat carotid body cells based on the oxygen sensitivity of voltage-gated potassium channels. In the present study, we attempted to determine the correlation between cell types (glomus cells, sheath cells, and subtypes of glomus cells) and oxygen sensitivity of potassium channels. Further, changes in membrane potentials in response to hypoxia were also examined. Carotid body cells harvested from adult cats were cultured, and a whole cell patch clamp method was applied to determine the oxygen sensitivity of outward current. The tested cells were identified by Lucifer Yellow in the patch pipette. Glomus cells and sheath cells were immunocytochemically identified using tyrosine hydroxylase (TH) and glial fibrillary acidic protein (GFAP) as markers. The cells whose outward current was inhibited by hypoxia showed TH-immunoreactivity but not GFAP- immunoreactivity. The cells whose outward current was not sensitive to hypoxia were GFAP-positive or TH-negative. One TH-positive cell had oxygen- insensitive outward current. The resting membrane potentials of the cells having oxygen-sensitive outward current were significantly higher (-55 ± 3 mV) than those of the cells having oxygen-insensitive outward current (-35 ± 2 mV). The former type of cells was depolarized during hypoxia, but not the latter type of cells. These results suggest that most glomus cells of the adult cat carotid body possess oxygen-sensitive potassium channels and are depolarized in response to hypoxia. On the other hand, sheath cells and possibly a small fraction of glomus cells possess oxygen-insensitive potassium channels and their membrane potential is not affected by hypoxia.

Original languageEnglish (US)
Pages (from-to)229-238
Number of pages10
JournalBrain research
Volume789
Issue number2
DOIs
StatePublished - Apr 13 1998

Keywords

  • Chemoreceptor
  • Glial fibrillary acidic protein
  • Oxygen
  • Patch clamp
  • Potassium channel
  • Tyrosine hydroxylase

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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